Bicomponent elastic fiber composite material, elastic multifilament fiber including the composite material, and the manufacturing method for the same

ABSTRACT

A bicomponent elastic fiber composite material, which has a linear density of 20-150 deniers, a stretchability of 300-600%, and a deformation rate of 0-25% after stretching to 400%. The bicomponent elastic fiber composite material includes an inner core fiber and a sheath outer layer, wherein the inner core fiber includes a polystyrne copolymer material of a styrene-butadiene block copolymer (SBS), a styrene-ethylene-butylene-styrene block copolymer (SEBS) or a thermoplastic polyolefin elastomer (TPO), or includes a thermoplastic polystyrene elastomer (TPS). The sheath outer layer includes polypropylene (PP) or polyethylene (PE). Thereby, the present invention can realize zero pollution while recycled and reused. In addition, the present invention has excellent properties of elasticity, dyeability, acid and alkali resistance, quick-drying and non-absorbency, antibacterial and deodorizing, and has a soft texture. Further, the elastic multifilament fiber including the composite material has the full effect of the bicomponent elastic fiber composite material.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority of Taiwanese patent application No.108101077, filed on Jan. 10, 2019, which is incorporated herewith byreference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a fiber composite material, inparticular, to a bicomponent elastic fiber composite material havingelasticity which is formed by using a thermoplastic elastic material toconstitute an inner core fiber, using a thermoplastic material toconstitute a sheath outer layer, and cladding the sheath outer layer toa surface of the inner core fiber; an elastic multifilament fiberincluding the composite material; and a manufacturing method for thesame.

2. The Prior Arts

In recent years, with the prevalence of the fashion of leisure sports,the sales volume of functional sports fabrics have also increased.Meanwhile, the demand for fabric functionality has gradually increasedas well. For example, in addition to being lighter, moisture wicking,antibacterial, and deodorant, it is further desired that an elasticfiber fabric having a close-fitting comfort can reduce restraintfeeling. Therefore, in material technology, there is a need for moremoving possibility between stretching force and restoring force, and aneed for striking an optimal balance between functionality and comfort.

Since the process steps have been improved year by year, the elastictextile fiber technology has already have advantages ofeasier-to-manufacturing, processing, durability, rapid productionefficiency, and low cost and has been widely used in many functionalsports fabrics.

However, in the conventional art, the general elastic fiber fabric stillhas the following disadvantages to be overcome.

First, take an elastic fiber fabric made of a diene-based elastic fiber(elastic thread) as an example, it is not suitable for a user who hassevere allergic symptoms to latex. Generally, synthetic rubber such asneoprene, butyl rubber, and the like is used instead to avoid allergicreactions. However, the cost of synthetic rubber is generally higher, sothat the elastic fiber fabric made of synthetic rubber is lesscompetitive.

In addition, the materials which are more widely used to make elasticfiber fabrics also include polyurethane fiber (Spandex). However, thereare several problems for polyurethane fiber: first, there are problemsof difficulties in recycling; second, it produces dioxin which seriouslypollutes the environment while burning; third, it has poor weatherresistance and light resistance which affect the service life.

Further, polyether ester elastic fibers are also common materials forelastic fiber fabrics. However, since the fiber hardness of thepolyether ester elastic fiber is higher, it affects the softness of theelastic fiber fabric. Meanwhile, since the processing conditions arealso rigorous, more precise processing machines must be used and theprice is considerably expensive as a result.

Moreover, each of the elastic fibers is formed by directly drawing theone-component elastomer, resulting in an inter-adhesion problem amongmultiple elastic fibers of the elastic fiber fabric.

In particular, the fabric has a high-temperature requirement whiledyeing and setting (thermal dimensional stability, antiwrinkling).Further, for example, elastic fibers of polyurethane fibers (Spandex),polyester, and polyamide (Nylon) must withstand a high temperature of180-240° C. with thermosetting. Moreover, the thermosetting temperatureof such polyurethane elastic fibers is above 180° C., which is higherthan the melting point of polypropylene (PP) fibers of 160° C. As aresult, after cladding the polypropylene fibers to such polyurethaneelastic fibers to form yarns, the effect of thermosetting is affected bythe difference in glass transition (Tg) between different materials. Itis well known that when the temperature is too low, the elastic fiberfabric cannot be wrinkle-free and stabilized in size; however, when thetemperature is too high, the polypropylene fiber will convert into fluidstate, lose its fiber configuration, and will be unusable as a result.

The existing polypropylene fiber is a fiber which becomes colored byadding colored masterbatch while producing the fibers. However, thiswill result in lower color diversity than the traditional method inwhich the cloth is dyed and finished after weaving.

For example, the polyester fiber has a dyeing temperature of about130-135° C., the Nylon fiber (Nylon 66) has a dyeing temperature ofabout 110° C., and the OP elastic yarn has a dyeing temperature of about125° C., which is quite high. In particular, although the OP elasticyarn (polymerized yarn) has dyeability, it is not colored, that is, thedye adheres only at the surface, so the overall dyeing fastness isextremely poor.

SUMMARY OF THE INVENTION

A primary objective of the present invention is to provide a bicomponentelastic fiber composite material, wherein the inner core fiber isconstituted of a thermoplastic elastic material and the sheath outerlayer is constituted of a thermoplastic material, so that the presentinvention has excellent elasticity.

Another objective of the present invention is to provide a bicomponentelastic fiber composite material which has excellent dyeability.

Yet another objective of the present invention is to provide abicomponent elastic fiber composite material which has the advantages ofacid and alkali resistance, quick-drying and non-absorbency,antibacterial and deodorizing, recyclable, and reusable. It has a softtexture, which is suitable for applying in thin coats, close-fittingclothing or diapers, capable of making the dressing more comfortable.

Still another objective of the present invention is to provide anelastic multifilament fiber including the composite material and themanufacturing method for the same, wherein the made elasticmultifilament fiber has the full effect of the bicomponent elastic fibercomposite material.

In order to achieve the objectives mentioned above, the presentinvention provides a bicomponent elastic fiber composite material, whichis a bicomponent fiber structure with a core sheath or a core spun,comprising an inner core fiber and a sheath outer layer. The inner corefiber includes a polystyrene copolymer material of a styrene-butadieneblock copolymer (SBS), a styrene-ethylene-butylene-styrene blockcopolymer (SEBS) or a thermoplastic polyolefin elastomer (TPO), orincludes a thermoplastic polystyrene elastomer (TPS). The sheath outerlayer clads to an outer surface of the inner core fiber and includespolypropylene (PP) or polyethylene (PE).

Wherein a ratio of a thickness of the sheath outer layer to a radius ofthe inner core fiber is between 1:9 to 9:1.

Wherein the bicomponent elastic fiber composite material has a lineardensity of 20-150 deniers and a stretchability of 300-600%.

Wherein the bicomponent elastic fiber composite material has adeformation rate of 0-25% after stretching to 400%.

Preferably, the inner core fiber has a stretchability of 100-600%.

Preferably, the sheath outer layer has dyeability.

Preferably, the polypropylene has a graft-dyeing base for dyeing.

Preferably, the ratio of the thickness of the sheath outer layer to theradius of the inner core fiber is 9:1, and the bicomponent elastic fibercomposite material has a linear density of 30 deniers and astretchability of 500%, and the bicomponent elastic fiber compositematerial has a deformation rate of 1% after stretching to 400%.

In order to achieve the objectives mentioned above, the presentinvention provides a manufacturing method for an elastic multifilamentfiber including a composite material, which includes the followingsteps:

a stretching step: stretching a bicomponent elastic fiber compositematerial to several times;

a surrounding step: commonly surrounding a plurality of surroundingfibers to outside of the bicomponent elastic fiber composite material,and wherein an elasticity of each of the surrounding fibers is lowerthan that of the bicomponent elastic fiber composite material;

an air entangling step: commonly forming a plurality of air entanglementknots on the plurality of surrounding fibers and the bicomponent elasticfiber composite material to form an elastic multifilament fiber, andwherein the plurality of air entanglement knots divide the elasticmultifilament fiber into a plurality of sections; and

a relaxing step: relaxing the bicomponent elastic fiber compositematerial such that the elastic multifilament fiber contracts back to anormal state by the deformation rate of the bicomponent elastic fibercomposite material, and thus, in each section of the elasticmultifilament fiber, a length of the bicomponent elastic fiber compositematerial is equal to a distance between adjacent two air entanglementknots, and a length of each of the surrounding fibers is greater thanthe distance between adjacent two air entanglement knots.

Preferably, the bicomponent elastic fiber composite material isstretched to three times in the stretching step.

Preferably, the material of each of the surrounding fibers is polyester.

In order to achieve the objectives mentioned above, the presentinvention provides an elastic multifilament fiber including a compositematerial, which includes a bicomponent elastic fiber composite materialand a plurality of surrounding fibers.

Wherein the plurality of surrounding fibers commonly surround outside ofthe bicomponent elastic fiber composite material and commonly contactthe bicomponent elastic fiber composite material by a plurality of airentanglement knots, and an elasticity of each of the surrounding fibersis lower than that of the bicomponent elastic fiber composite material.

Wherein the plurality of air entanglement knots divide the elasticmultifilament fiber into a plurality of sections

Wherein in each section of the elastic multifilament fiber, a length ofthe bicomponent elastic fiber composite material is equal to a distancebetween adjacent two air entanglement knots, and a length of each of thesurrounding fibers is greater than the distance between adjacent two airentanglement knots.

Preferably, the material of each of the surrounding fibers is polyester.

The effect of the present invention is that the inner core fiber isconstituted of a thermoplastic elastic material and the sheath outerlayer is constituted of a thermoplastic material, such that thebicomponent elastic fiber composite material and the elasticmultifilament fiber including the composite material of the presentinvention both have excellent elasticity.

Further, the bicomponent elastic fiber composite material and theelastic multifilament fiber including the composite material of thepresent invention can provide excellent dyeability by the dyeable sheathouter layer.

Moreover, the bicomponent elastic fiber composite material and theelastic multifilament fiber including the composite material of thepresent invention can both provide the advantages of acid and alkaliresistance, quick-drying and non-absorbency, antibacterial anddeodorizing, recyclable, and reusable. It has a soft texture, which issuitable for applying in thin coats, close-fitting clothing or diapers,capable of making the dressing more comfortable.

In addition, the polypropylene (PP) constituting the sheath outer layerhas a characteristic of low-temperature dyeing itself (a melting pointabout 70-110° C. lower than 160° C.), which is far lower than 130-135°C. of polyester (PET), 110° C. of nylon (Nylon 66), 125° C. of OPelastic yarn, such that the thermal energy and the dyeing time can bereduced to achieve energy-saving effect.

Furthermore, the bicomponent elastic fiber composite material of thepresent invention can utilize the sheath outer layer and the inner corefiber for one-time fiber drawing production, which not only has asimpler production process but also has a lower raw material cost thanthe commercially available elastic yarn (Spandex). Further, there isalmost no pollutant generated during the production process. Moreover,it is very easy to recycle and reuse to achieve the circular economy ofrecycling and reuse.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating the structure of a bicomponentelastic fiber composite material of the present invention;

FIG. 2 is a cross-sectional view illustrating an elastic fiber fabricproduced by feeding a plurality of bicomponent elastic fiber compositematerials of the present invention into a loom in a multifilamentmanner;

FIG. 3 is a flow chart illustrating the manufacturing method for anelastic multifilament fiber of the present invention;

FIG. 4 is a schematic view illustrating the stretching step, surroundingstep, air entangling step of the manufacturing method for the elasticmultifilament fiber of the present invention; and

FIG. 5 is a schematic view illustrating the relaxing step of themanufacturing method for the elastic multifilament fiber of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Embodiments of the present invention will be described in more detailbelow with reference to the drawings and the reference numerals, suchthat those skilled in the art can implement it after studying thisspecification.

Please refer to FIG. 1 which is a schematic view illustrating thestructure of a bicomponent elastic fiber composite material 1 of thepresent invention. The present invention provides a bicomponent elasticfiber composite material 1 comprising an inner core fiber 10 and asheath outer layer 20. The sheath outer layer 20 clads to an outersurface of the inner core fiber 10, wherein the inner core fiber 10 isconstituted of a thermoplastic elastic material and the sheath outerlayer 20 is constituted of a thermoplastic material, and thus thebicomponent elastic fiber composite material 1 of the present inventionhas excellent elasticity. Preferably, the sheath outer layer 20 isconstituted of a dyeable thermoplastic material, and thus thebicomponent elastic fiber composite material 1 of the present inventionmay also have dyeability.

In particular, the bicomponent elastic fiber composite material 1 of thepresent invention is essentially a bicomponent fiber structure with acore sheath or a core spun. In particular, the bicomponent elastic fibercomposite material 1 of the present invention has a linear density of20-150 deniers and a stretchability of 300-600%. The bicomponent elasticfiber composite material 1 of the present invention has a deformationrate of 0-25% after stretching to 400%.

Further, the inner core fiber 10 includes a polystyrene copolymermaterial of a styrene-butadiene block copolymer (SBS), astyrene-ethylene-butylene-styrene block copolymer (SEBS) or athermoplastic polyolefin elastomer (TPO), or includes a thermoplasticpolystyrene elastomer (TPS). Furthermore, the inner core fiber 10 has astretchability of 100-600%.

It is well known that the thermoplastic polystyrene elastomers (TPS)mentioned above, which are also referred to as styreneic blockcopolymers or SBCs for short, are a type of thermoplastic elastomer withthe largest production currently in the world and having the propertiesmost similar to that of rubber. Currently, there are mainly four typesin the species of SBCs series, that is: styrene-butadiene blockcopolymer (SBS), styrene-isoprene-styrene block copolymer (SIS),styrene-ethylene-butylene-styrene block copolymer (SEBS) andstyrene-ethylene-propylene-styrene block copolymer (SEPS), wherein SEBSand SEPS are hydrogenated copolymers of SBS and SIS, respectively.

Further, the hard segment of the thermoplastic polyolefin elastomer(TPO) is a polyolefin material such as polypropylene (PP) orpolyethylene (PE) or the like, wherein the soft segment thereof is arubber such as ethylene propylene diene monomer (EPDM) and the like.Generally, it is formed by polymerization using metallocene as acatalyst, wherein the hard segment and the soft segment are directlycombined by a covalent bond, so that this kind of the thermoplasticpolyolefin elastomer (TPO) is also referred to as M-POE.

In addition, the sheath outer layer 20 may include polypropylene (PP) orpolyethylene (PE) and has dyeability. A ratio of a thickness of thesheath outer layer 20 to a radius of the inner core fiber 10 may bebetween 1:9 to 9:1 for adjusting the best properties of softness,stretchability, restoring rate, tensile stress and the like according topractical needs. The polypropylene mentioned above may preferably havegraft-dyeing bases for enhancing dyeability.

In a preferred embodiment, the ratio of the thickness of the sheathouter layer 20 to the radius of the inner core fiber 10 is 9:1, and thebicomponent elastic fiber composite material 1 has a linear density of30 deniers and a stretchability of 500%, and the bicomponent elasticfiber composite material 1 has a deformation rate of 1% after stretchingto 400%.

Since the polypropylene (PP) constituting the sheath outer layer 20 hasa characteristic of low-temperature dyeing itself (about 70-110° C.lower than 160° C.), which is much lower than 180° C. of polyurethanefibers (Spandex), 130-135° C. of polyester (PET), 110° C. of Nylon 66,and 125° C. of the OP elastic yarn, so the thermal energy and the dyeingtime can be reduced to achieve energy-saving effect.

Furthermore, the present invention can utilize the sheath outer layer 20and the inner core fiber 10 for one-time fiber drawing production, whichnot only has a simpler production process but also has a lower rawmaterial price than the commercially available elastic yarn (Spandex).Further, there is almost no pollutant generated during the productionprocess. Moreover, it is very easy to recycle and reuse to achieve thecircular economy of recycling and reuse.

In summary, the bicomponent elastic fiber composite material 1 of thepresent invention is characterized in that it has the advantages of acidand alkali resistance, quick-drying and non-absorbency, antibacterialand deodorizing, recyclable, and reusable. It has a soft texture, whichis suitable for applying in thin coats, close-fitting clothing ordiapers, capable of making the dressing more comfortable. Particularly,it has high elasticity and is easy to be dyed, and the dyeing fastnessthereof is better. Furthermore, it can be mix-weaved with other fibersinto functional fabrics with different high functionality, such assports clothes or close-fitting clothing.

In addition, the bicomponent elastic fiber composite material 1 of thepresent invention has the characteristics of lower glass transitionpoint, which can satisfy the dyeing and setting conditions of thepolypropylene fiber while improving the problem of the fabric inboarding (for example, thermal dimensional stability), and therebyimproved the situation that the yarn exchanges between face and back orthe color fastness is deteriorated easily because the fibers are notcapable of being dyed when the fiber is interweaved with fibers such aspolyesters.

Further, fibers utilizing polypropylene having the graft-dyeing bases asthe sheath outer layer 20 can have a better dyeability (SDY 110° C.dyeing) than the general polypropylene fiber, and have the same grade ofwashing fastness (SDY 110° C. dyeing) as polyester (PET). In particular,the practical needs of optimum properties of softness, stretchability,restoring rate, tensile stress and the like can be satisfied byadjusting the ratio of the thickness of the sheath outer layer 20 to theradius of the inner core fiber 10.

The following are explanations about further producing two types ofelastic fiber fabrics by using the bicomponent elastic fiber compositematerial 1 of the present invention.

First, please refer to FIG. 2 which is a cross-sectional viewillustrating an elastic fiber fabric 100 produced by feeding a pluralityof bicomponent elastic fiber composite materials 1 of the presentinvention into a loom in a multifilament manner. A plurality of thebicomponent elastic fiber composite materials 1 of a preferredembodiment of the present invention are directly fed into a loom (notshown) in a multifilament manner to be woven into an elastic fiberfabric 100. Thus, the made elastic fiber fabric 100 also has the fulleffect of the described bicomponent elastic fiber composite material 1.

Next, please refer to FIGS. 3 to 5. FIG. 3 is a flow chart of themanufacturing method for an elastic multifilament fiber 3 of the presentinvention; FIG. 4 is a schematic view illustrating the stretching step,surrounding step, air entangling step of the manufacturing method forthe elastic multifilament fiber 3 of the present invention; and FIG. 5is a schematic view illustrating the relaxing step S40 of themanufacturing method for the elastic multifilament fiber 3 of thepresent invention. The present invention provides a manufacturing methodfor an elastic multifilament fiber 3, which includes a stretching stepS10, a surrounding step S20, an air entangling step S30, and a relaxingstep S40.

Stretching step S10: stretching a bicomponent elastic fiber compositematerial 1 to several times. Wherein, it is preferable to be stretchedto three times.

Surrounding step S20: commonly surrounding a plurality of surroundingfibers 2 to outside of the bicomponent elastic fiber composite material1, and wherein an elasticity of each of the surrounding fibers 2 islower than that of the bicomponent elastic fiber composite material 1.Preferably, the material of each of the surrounding fibers 2 ispolyester, which is almost inelastic.

Air entangling step S30: commonly forming a plurality of airentanglement knots P on the plurality of surrounding fibers 2 and thebicomponent elastic fiber composite material 1 to form an elasticmultifilament fiber 3. The plurality of air entanglement knots P dividethe elastic multifilament fiber 3 into a plurality of sections 31.

Relaxing step S40: relaxing the bicomponent elastic fiber compositematerial 1 such that the elastic multifilament fiber 3 contracts back toa normal state by the deformation rate of the bicomponent elastic fibercomposite material 1. So that, in each section 31 of the elasticmultifilament fiber 3, a length of the bicomponent elastic fibercomposite material 1 is equal to a distance between adjacent two airentanglement knots P, and a length of each of the surrounding fibers 2is greater than the distance between adjacent two air entanglement knotsP. The made elastic multifilament fiber 3 has the full effect of thedescribed bicomponent elastic fiber composite material 1.

A plurality of bicomponent elastic multifilament fibers 3 of the presentinvention may be further fed into a loom (not shown) to be woven into anelastic fiber fabric (not shown). Thus, the made elastic fiber fabricalso has the full effect of the described bicomponent elastic fibercomposite material 1.

The mentioned above are only preferred embodiments for explaining thepresent invention but intend to limit the present invention in anyforms, so that any modifications or verification relating to the presentinvention made in the same spirit of the invention should still beincluded in the scope of the invention as intended to be claimed.

What is claimed is:
 1. A bicomponent elastic fiber composite material,which is a bicomponent fiber structure with a core sheath or a corespun, comprising: an inner core fiber including a polystyrene copolymermaterial of a styrene-butadiene block copolymer (SBS), astyrene-ethylene-butylene-styrene block copolymer (SEBS) or athermoplastic polyolefin elastomer (TPO), or including a thermoplasticpolystyrene elastomer (TPS); and a sheath outer layer cladding to anouter surface of the inner core fiber, and including polypropylene (PP)or polyethylene (PE); wherein a ratio of a thickness of the sheath outerlayer to a radius of the inner core fiber is between 1:9 to 9:1; whereinthe bicomponent elastic fiber composite material has a linear density of20-150 deniers and a stretchability of 300-600%; and wherein thebicomponent elastic fiber composite material has a deformation rate of0-25% after stretching to 400%.
 2. The bicomponent elastic fibercomposite material according to claim 1, wherein the inner core fiberhas a stretchability of 100-600%.
 3. The bicomponent elastic fibercomposite material according to claim 1, wherein the sheath outer layerhas dyeability.
 4. The bicomponent elastic fiber composite materialaccording to claim 3, wherein the polypropylene has a graft-dyeing basefor dyeing.
 5. The bicomponent elastic fiber composite materialaccording to claim 1, wherein the ratio of the thickness of the sheathouter layer to the radius of the inner core fiber is 9:1, and thebicomponent elastic fiber composite material has a linear density of 30deniers and a stretchability of 500%, and the bicomponent elastic fibercomposite material has a deformation rate of 1% after stretching to400%.
 6. A manufacturing method for an elastic multifilament fiber,comprising the following steps: a stretching step: stretching abicomponent elastic fiber composite material to several times; asurrounding step: commonly surrounding a plurality of surrounding fibersto outside of the bicomponent elastic fiber composite material, andwherein an elasticity of each of the surrounding fibers is lower thanthat of the bicomponent elastic fiber composite material; an airentangling step: commonly forming a plurality of air entanglement knotson the plurality of surrounding fibers and the bicomponent elastic fibercomposite material to form an elastic multifilament fiber, and whereinthe plurality of air entanglement knots divide the elastic multifilamentfiber into a plurality of sections; and a relaxing step: relaxing thebicomponent elastic fiber composite material such that the elasticmultifilament fiber contracts back to a normal state by the deformationrate of the bicomponent elastic fiber composite material, and thus, ineach section of the elastic multifilament fiber, a length of thebicomponent elastic fiber composite material is equal to a distancebetween adjacent two air entanglement knots, and a length of each of thesurrounding fibers is greater than the distance between adjacent two airentanglement knots; wherein the bicomponent elastic fiber compositematerial is a bicomponent fiber structure with a core sheath or a corespun, comprises an inner core fiber and a sheath outer layer; whereinthe inner core fiber includes a polystyrene copolymer material of astyrene-butadiene block copolymer (SBS), astyrene-ethylene-butylene-styrene block copolymer (SEBS) or athermoplastic polyolefin elastomer (TPO), or includes a thermoplasticpolystyrene elastomer (TPS); wherein the sheath outer layer clads to anouter surface of the inner core fiber, and includes polypropylene (PP)or polyethylene (PE); wherein a ratio of a thickness of the sheath outerlayer to a radius of the inner core fiber is between 1:9 to 9:1; whereinthe bicomponent elastic fiber composite material has a linear density of20-150 deniers and a stretchability of 300-600%; and wherein thebicomponent elastic fiber composite material has a deformation rate of0-25% after stretching to 400%.
 7. The manufacturing method according toclaim 6, wherein the bicomponent elastic fiber composite material isstretched to three times in the stretching step.
 8. The manufacturingmethod according to claim 6, wherein the material of each of thesurrounding fibers is polyester.
 9. The manufacturing method accordingto claim 6, wherein the sheath outer layer has dyeability.
 10. Themanufacturing method according to claim 6, wherein the polypropylene hasa graft-dyeing base for dyeing.
 11. The manufacturing method accordingto claim 6, wherein the ratio of the thickness of the sheath outer layerto the radius of the inner core fiber is 9:1, and the bicomponentelastic fiber composite material has a linear density of 30 deniers anda stretchability of 500%, and the bicomponent elastic fiber compositematerial has a deformation rate of 1% after stretching to 400%.
 12. Anelastic multifilament fiber, comprising: a bicomponent elastic fibercomposite material and a plurality of surrounding fibers; wherein thebicomponent elastic fiber composite material is a bicomponent fiberstructure with a core sheath or a core spun, comprises an inner corefiber and a sheath outer layer; wherein the inner core fiber includes apolystyrene copolymer material of a styrene-butadiene block copolymer(SBS), a styrene-ethylene-butylene-styrene block copolymer (SEBS) or athermoplastic polyolefin elastomer (TPO), or includes a thermoplasticpolystyrene elastomer (TPS); wherein the sheath outer layer clads to anouter surface of the inner core fiber, and includes polypropylene (PP)or polyethylene (PE); wherein a ratio of a thickness of the sheath outerlayer to a radius of the inner core fiber is between 1:9 to 9:1; whereinthe bicomponent elastic fiber composite material has a linear density of20-150 deniers and a stretchability of 300-600%; wherein the bicomponentelastic fiber composite material has a deformation rate of 0-25% afterstretching to 400%; wherein the plurality of surrounding fibers commonlysurround outside of the bicomponent elastic fiber composite material andcommonly contact the bicomponent elastic fiber composite material by aplurality of air entanglement knots, and an elasticity of each of thesurrounding fibers is lower than that of the bicomponent elastic fibercomposite material; wherein the plurality of air entanglement knotsdivide the elastic multifilament fiber into a plurality of sections; andwherein in each section of the elastic multifilament fiber, a length ofthe bicomponent elastic fiber composite material is equal to a distancebetween adjacent two air entanglement knots, and a length of each of thesurrounding fibers is greater than the distance between adjacent two airentanglement knots.
 13. The elastic multifilament fiber according toclaim 12, wherein the material of each of the surrounding fibers ispolyester.
 14. The elastic multifilament fiber according to claim 12,wherein the sheath outer layer has dyeability.
 15. The elasticmultifilament fiber according to claim 12, wherein the polypropylene hasa graft-dyeing base for dyeing.
 16. The elastic multifilament fiberaccording to claim 12, wherein the ratio of the thickness of the sheathouter layer to the radius of the inner core fiber is 9:1, and thebicomponent elastic fiber composite material has a linear density of 30deniers and a stretchability of 500%, and the bicomponent elastic fibercomposite material has a deformation rate of 1% after stretching to400%.